Power factor correction is often used in electric power systems and between power sources and loads in order to synchronize the input current and the input voltage before it is delivered to the load. Power factor correction can provide many benefits to the electric power system and the load, such as prolonged life and energy efficiency.
Traditionally, power factor correction circuitry is designed as voltage based power factor correction. Such circuitry is used in constant voltage systems, and the input current waveform is made to match the input voltage waveform. However, in certain industries, such as airfield lighting, the existing infrastructure, requires current based systems which require a constant current power source rather than a constant voltage power source. Specifically, in the area of airfield lighting, constant current systems are traditionally used because of the need for consistent brightness across the plurality of light fixtures coupled in series and being powered by the same power source. Because a constant current power supply can provide the same level of current to each of the light fixtures, it became the standard form of power distribution in the area of airfield lighting. Though lighting technology has become more sophisticated in recent years, the infrastructure has remained a current based system. However, power factor correction techniques used for voltage based systems which receive a constant voltage generally cannot be used for current based systems.
Additionally, in many modern lighting systems, light fixtures are able to communicate with a central controller. For example, a light fixture may send a signal to the central controller indicative of operational data or error. The central controller may also send a signal to a light fixture containing an operational command or status request. In the airport lighting industry, such communication can be done through power line communication, in which communication and control signals can be sent between the central controller and light fixtures. Typically, an amplifier is used to add a higher frequency communication signal on top of the power line signal, such as a typical 60 hertz power line signal. A receiver is then used at the receiving end to decode the communication signal. Consequently, such communication systems typically require additional hardware and present several challenges, such as attenuation, error checking, and slow hardware.